Integrated ocean observation & forecasting

The Institute of Oceanography continued to support and upgrade the observing and forecasting components of the POSEIDON operational oceanography system using funds from European and national projects:

The existing mooring infrastructure was extensively renewed and the overall POSEIDON observing capacity was expanded with the addition of new monitoring platforms including also the first seabed cabled platform through national structural funds (KRIPIS project for IO, Greek Argo and Hellenic EMSO projects, EEA 2009-2014 predefined project)

New recording capabilities were tested and important know-how transfer was made through the participation of the IO in several EU I3 projects (Jerico, Jerico Next, FixO3).

Products and services were developed through the participation of the IO in the Mediterranean observing and forecasting component of the Copernicus Marine Environment Monitoring Service (CMEMS).

During this period, the POSEIDON observing system was upgraded from a buoy network into a multi-node integrated observatory which can make use of data that come from several platforms, providing the capabilities for ocean monitoring on multiple scales, ranging from ocean state to ocean variability. Moreover, the IO has been assigned the responsibility to lead the integration of the relevant oceanographic activities on national scale in order to build the marine node of the Greek national research infrastructure map. This effort will be realized through funding that will be available for the period 2018-2020.

The main developments achieved during the reporting period are presented hereafter:

Observing component

Fixed Stations: Three multiparametric buoys are deployed in the S. Aegean (E1-M3A), N. Aegean (Athos) and Ionian Seas (Pylos) and provide meteorological, physical and biochemical (O2, Chl-a) data. An extensive renewal and upgrade of both the recording sensors (new atmospheric and dissolved CO₂ sensor, new pH sensor) and of the supporting hardware was realized through the EEA 2009-2014 predefined project, enhancing the mooring component’s performance and sustainability. The coastal component of the mooring network is composed by another three buoys that are deployed close to the coasts of Athens (Saronikos buoy-SB), Heraklion (Heraklion Coastal buoy-HCB) and Mykonos, and provides possibilities to study the coastal-open sea processes interaction (e.g. wave dynamics, exchanges of matter, extreme events spatial extend).

Argo Floats: The Greek Argo infrastructure (www.greekargo.gr), contributed with 17 deployed floats between 2014 and 2017 (five of which were Bio-Argos) further contributes to the international ARGO communities efforts to monitor the ocean dynamics and the biochemical properties of the water column in the Aegean/Ionian and the Eastern Mediterranean Sea.

Gliders: Two SeaExplorer gliders were added to the monitoring platforms of the POSEIDON system at the end of 2015 through the implementation of nationally funded KRIPIS project. It is among the POSEIDON’s future plans for the implementation of an endurance line in the Cretan Sea, as continuous monitoring through the use of the glider component is expected to contribute to further knowledge of the seasonal variability of the flow field, whilst also collecting also evidence of the intermediate or deep-water formation events that are known to occur in the area.

FerryBox System: The existing Poseidon FerryBox system has been installed in a new Ferry line and was upgraded with a high precision thermosalinograph for the study of the surface water formation as well as new sensor for dissolved oxygen.

Deep Seabed cabled platform: The construction of the seabed platform that was funded through the EMSO-HELLAS project suffered from a number of serious mechanical malfunctions that caused an extended delay in the expected delivery date. The platform hosts a series of oceanographic instruments for the continuous recording of CTD, ADCP, pH, O₂, Fluorescence, Turbidity, hydrostatic pressure (capturing also tsunami events) combined with seismological and gravitational data as well as video and bioacoustics data. The platform will be deployed in a close distance from the Pylos mooring at a depth of 1700 m.

Calibration facilities: The existing calibration laboratory was upgraded and emphasis was given on optical sensors that are widely used for the recording of several biochemical parameters (e.g. fluorescence, turbidity and oxygen). The lab has hosted a transnational calibration experiment within the JERICO TNAs projects and participates in international evaluation exercise for salinity measurements. The Poseidon calibration lab is part of the new established European Oceanographic Calibration Labs Network and it is involved in several networking activities under the framework of the JPI-Oceans.

Forecasting component

I.2.1 Development and implementation of Atmosphere-Ocean fully coupled models

Two-way coupling between the atmosphere and the waves: The research effort within the MyWave FP7 project resulted in the development of a fully coupled forecasting system for the atmospheric circulation and the wind waves.

Two-way coupling between hydrodynamics (ocean circulation) and waves: Within the Mediterranean component of the Copernicus Marine Service (CMEMS MED MFC), a coupled wave-current numerical modelling system has been developed and validated against observations for a 5-year period between 2009 and 2013.

Two-way coupling between hydrodynamics (ocean circulation) and the atmosphere: This direction is currently under development. Common efforts with the Atmosphere and Climate Dynamics Group of Harokopio University who has the leading role have resulted in coupling the NEMO hydrodynamic model with CHAOS modelling system (WRF 2-way coupled to WAM) in terms of exchanging heat, water and momentum fluxes over the Mediterranean and the Black Seas in fully coupled mode.

I.2.2 Upgrade of the existing numerical modeling infrastructure

Development and implementation of a high resolution wave forecasting system covering the whole Mediterranean Sea at 1/24^o resolution: The Operational Oceanography Group of the IO has developed and implemented within the framework of the Mediterranean component (MED MFC) of the Copernicus Marine Environment Monitoring Service (CMEMS), an operational wave forecasting system for the Mediterranean Sea.

Development and implementation of a high resolution operational forecasting system for the Ionian Sea at ~2 km resolution: The forecasting system is now fully operational.Development and implementation of a very high resolution operational forecasting system for circulation and waves for the Saronikos Gulf. Exploitation of satellite and in situ observations through data assimilation in order to improve the forecasting capacity of the POSEIDON numerical modelling infrastructure.

Satellite skin SST: In order to improve skin SST data assimilation schemes and enhance the exploitation of swath SST data, a dynamical – statistical observation operator capable of representing the SST diurnal cycle has been developed within the SOSSTA research project and implemented and thoroughly tested within the assimilation scheme of the POSEIDON forecasting system (Aegean Sea). A new hybrid ensemble based kalman filter has been developed and implemented with the POSEIDON Mediterranean operational ecosystem model, for data assimilation of satellite Chl-a. The next step is to employ the developed algorithm for the assimilation of satellite Chl-a data from Copernicus marine data stream on operational basis, in order to provide a corrected state of the Mediterranean ecosystem state within POSEIDON forecast system.

Climate variability and impact on marine ecosystems

Long range (climatic) changes in thermohaline circulation

The IO will continue its longstanding research effort in monitoring the climatic change of the marine ecosystem. This will be achieved by implementing research cruises in the Eastern Mediterranean, focusing particularly on specific points of interest (e.g. the deep basins of the north Aegean, Cretan and Ionian Seas). The monitoring of physical and biochemical parameters in these areas is a key factor for diagnosing new dense water formation events related to climate change. Surveys in the wider eastern Mediterranean area will reveal the circulation patterns and the ecosystemic functioning under the recently developed theories of quasi-decadal variations of the Mediterranean oceanic circulation. The deployment of moorings equipped with physical sensors as well as sediment traps in well-chosen key points in the Cretan Straits, will maintain the generation of long time-series of essential climate variables data, and thus help the understanding of Aegean Sea – Western Mediterranean interactions, and climate change trends.

Impact of climate variability on the structure and functioning of marine ecosystems

Building upon previous achievements, continuous effort will be placed on the study of the impact of climate variability on the ocean dynamics, biogeochemical cycles, the structure and functioning of marine ecosystems, and the biodiversity changes triggered by global warming.

The research is focused on the processes impacting the ecosystems, such as (i) changes in marine biodiversity related to global change at the species and community level and effects on ecosystem health and services, (ii) climate- and human-driven changes in ocean physics and chemistry (e.g. enhanced stratification, expansion of low-oxygen conditions, acidification, etc.) and associated impacts on biogeochemical cycles of carbon, nitrogen, phosphorus and other biogeochemically important elements (e.g. Fe, Mn).

Study of the role of atmospheric CO₂ in ocean acidification and impact on the marine organisms

The strongest progress of ocean acidification research is in the level of single species or strains with respect to their acclimated (short-term) physiological responses to the single driver ocean acidification. However, the interest of several scientists is the long-term response of communities, ecosystems and ecosystem services to several of environmental alterations. This is also the result that policy makers, ecosystem managers and fishermen long for. It is also important to have clear indications of the potential of marine organisms to adapt to ocean acidification and other environmental changes. Future ocean acidification research needs to expand from single to multiple drivers, from single species to communities and ecosystems and from acclimation to adaptation.

To address such issues the IO has a long-term commitment. There have been significant efforts to increase observations, however this work is a synergistic one and should involve in situ monitoring together with observing systems and research cruises, in order to create reliable projections to current and future climatic variability scenarios. To have a more realistic picture of the carbonate dynamics and whether carbon acts as a source or a sink to the atmosphere, further monitoring of its major parameters is needed. The IO needs to secure funding towards this research field. There should also be opportunities for large-scale integrative projects, long-term monitoring, and international collaborations. With this at hand, the IO could successfully be part of ocean acidification research networks and with the co-occurring environmental changes, it is more likely to continue research in this field and develop it further.

Paleo-environmental and paleo-climatic changes

Future studies in the paleoceanography/ paleoclimatology field will encompass multidisciplinary approaches addressing high temporal resolution climatic variability across the NE Mediterranean. In particular, the development of a comparative study of paleoceanographic – paleoclimatic conditions is planned, involving key areas with different oceanographic conditions (Ionian/Cretan/Aegean/Levantine Seas) as well as transitional and lagoonal environments over (a) the last climatic cycle (glacial/ interglacial) and (b) the last millennia, including the instrumental period. This is a crucial step towards improving our understanding of the climate and its variability (in response to natural and anthropogenic forcing) and the impact on the evolution of human societies in the NE Mediterranean, and will enable the detailed determination of the climate system sensitivity and clarify the pace of future climate changes.

The derived data will be available for the construction of a paleoceanographic model of the NE Mediterranean. The proposed research is based on the multidisciplinary combination of traditional and novel paleoceanographic methods, involving numerous researchers of different specialties, in an attempt to promote and intensify the paleoceanographic research on national & international level.

Paleoceanographic studies will extend to examine the deposition of authigenic carbonates in paleolakes that have been formed during the last glacial period along the Greek coastline. Such occurrences are numerous and may provide valuable information on upper Pleistocene climate variability with great detail.

Last but not least, the impact of long termed and abrupt climatic changes will be evaluated in respect to the evolution of the Eastern Mediterranean civilizations.The Eastern Mediterranean region bears a long history of human development, making it a truly unique experimental site to explore the complex interactions between climate, environment and human activity over a range of time scales from decadal to multi-centennial. With this in mind, improved knowledge regarding the influence of various climate events in the recent past and their impact on human societies can provide a better context for understanding how societies can adapt to and mitigate the effects of future climate change.

From the coast to the deep sea

Temporal and spatial determinations of shoreline displacement, sediment transport pathways and morphodynamic processes have been performed in a plethora of coastal areas and islands of the Aegean Sea (e.g., Attica coasts, NW Peloponnese coasts, Crete coasts, Messenian Gulf, NW Rhodes, SE Chios, SE Santorini, S Sifnos). State-of-the-art techniques, effective field practices and numerical models are applied to quantify the mechanisms of short- and/or long-term geomorphological changes in a coastal cell, caused by the synergy of natural and uncontrolled human activities. Basic components of coastal morphodynamics, i.e., major topographic/bathymetric changes, sediment dispersion patterns and dominant wave-current regime, are investigated through targeted and systematic monitoring projects. In particular:

(i) the seasonal and long-term 3D morphological modifications of the terrestrial and marine sectors of coasts are mapped using unmanned aerial vehicles, satellite imagery and multi- and single-beam echo sounder techniques;

(ii) the intensity of solid material mobilization and changes in the sediment volume are determined applying highly accurate GPS techniques; and

(iii) the local oceanographic processes are measured through the deployment of instrumentation of coastal and offshore monitoring, comprising acoustic Doppler current profilers, CTD profilers and time-series sediment traps.

All acquired data are processed using advanced numerical models such as the SWAN wave model (developed by the Delft University of Technology), RUSLE erosion prediction model (developed by the United States Department of Agriculture), and MIKE 21 coupled model (developed by the Danish Hydraulic Institute) for the simulation of coastal processes.

Health of the environment

Our research is related to eutrophication, chemical pollution including plastics, and anthropogenic noise. One pillar of our research aims to support the EU policies with the development of tools and the establishment of thresholds and/or background concentrations towards Good Environmental Status in the Greek Seas. We work on threshold values for nutrients, background concentrations for metals in seawater, sediment quality guidelines (SQGs), new integrated approaches from observation - to - diagnosis - to – mitigation of plastics and microplastics. A second pillar of our research is the investigation of the sources, fate and interactions with ecosystem functioning of contaminants, POPs, flame retardants, other contaminants of emerging concern as well as microplastics in the marine ecosystem of the eastern Mediterranean.

This is made possible through field and laboratory work, mesocosm experiments, chemical analyses of specific substances and toxicological effects on the organism level. Recently, a new research field related to underwater noise input and its anthropogenic impacts in the marine environment, takes advantage of acoustic Argo floats in the Greek Seas, acquiring information about the ocean soundscape.

Geodynamics and Marine Geohazards

Long-term tectonics, kinematics and basin formation

Research activities on Long-term Tectonics and Basin Formation focus on the following axes:

a) Integration of available data-sets (Fig. 1) (swath bathymetry, seismic profiles, GPS measurements, seismological data, etc), and the acquisition of new data across the Aegean, Hellenic Arc and Trench and the Mediterranean Ridge. Systematic marine geological and seismic profiling survey in the North Aegean Sea as well as in the South Aegean Sea and the Hellenic Trench will be continued.

b) The knowledge gap with regards to the crustal and lithospheric geometry below the Aegean microplate is the target of a collaborative effort between IO/HCMR, European and overseas partners. Their aim is to use passive recording techniques (receiver functions, ambient noise tomography) as well as active seismics to collect lithospheric-scale seismic profiles, on land and offshore, across the Hellenic Belt, the Aegean Sea and the Hellenic Arc and Trench system.

c) Building on the results of the IODP Expedition 381 “Corinth Drilling” to develop understanding of the evolution of the Corinth Rift. Preparation of relevant proposals in collaboration with European and Greek institutes and universities is already in progress.

Active Faulting & Seismic Potential, Volcanic/Hydrothermal Activity, Submarine Landslides, Tsunamis

The first comprehensive map of the offshore fault network and the interpretation of the kinematics of the faults in the Aegean Sea and the Hellenic Trench has been recently published. This is an ongoing effort aiming at continuous updating and refining the offshore fault map. IO along with the Geodynamic Institute (GI/NOA) and the Department of Geology of the Aristoteles University of Thessaloniki have proposed to design and build the new Greek Seismo-Tectonic Database, which will serve as the national database of information on active faults, earthquakes, seismicity etc.

In the framework of HELPOS project, coordinated by GI/ NOA, IO will facilitate the link of the seismological station of EMSO-HELLAS Deep Seafloor Observatory that will be deployed off the W. Peloponnese, with the National Seismological Network. Similarly, the pressure sensor mounted on EMSO-HELLAS will be linked with the Hellenic Tsunami Early Warning Center in GI/NOA during the HELPOS project. The spatial and temporal distribution of the volcanic/hydrothermal activity in the South Aegean and their relationship with the active faulting and seismicity remain among the foci of research on marine geohazards.

In addition, reliable reconstruction of the volcanic processes associated with the Minoan eruption and tsunami(s) and with the formation of Santorini caldera remains unresolved.
Systematic mapping of submarine landslides, identification of areas prone to landslides and potential tsunami source areas are among the research priorities of the IO.

Recent advances in bathymetric coverage and high-resolution seismic profiling, side scan sonar data and coring from various areas in the Aegean (e.g. EUROFLEETS2 LGT-AMORGOS-56 cruise) are used for the interpretation of mass transport deposits and their potential relationship with known tsunamis in the past. Elaboration of various scenarios for the generation and propagation of tsunamis are based on realistic simulations and studied source areas.

Cross Cutting Activities

Renewable energy resources in the marine environment

Research activities have focused on the estimation of wind, wave and hydrodynamic energy fields in the Hellenic Seas via a series of projects (POSEIDON, AVRA, FLOATMAST, CoCoNET, MUSES, PELAGOS, HybridBlue Energy, GLAFKI). The Institute of Oceanography (IO) became the principal scientific consultant in the field of offshore wind farms installation in the coastal zone in Greece, by providing a detailed coastal wave climate analysis to interesting parties and key actors as well as a smart wind chart evaluation tool. In addition, the IO has participated in the ELEMED project, and contributed to the evaluation of marine renewable energy sources for ship electrification.

• 

• 

• 

A Mediterranean Innovative Cluster in Marine Renewable Energy (MRE) sector has been established (Pelagos Project). The cluster is designed to enhance research and innovation capacities of all key actors related to Blue and Marine Industry as well as it implements a consolidated mix of innovative transnational activities and fosters linkages and collaborations among all the stakeholders of the Quadruple Helix Innovation Model (government, academia, industry, citizens) of Blue Growth in order to achieve knowledge and technology transfer within the MRE sector in the Mediterranean. The IO is the coordinator of the Greek Hub for Blue Energy with 56 members.

Underwater Geo-Archaeology

Progress in the field of Underwater Geoarchaeology has been accomplished by conducting new research projects, in collaboration with other Greek and foreign research Institutes. Several new projects were conducted in the Ionian Sea (‘Meganissi’, Corfu), the Gulf of Corinth (Itea), the Cyclades (Delos) and the Argolic Gulf (‘Terrasubmersa’), the latter in the vicinity of the Franchthi Cave, and were aiming at reconstructing Holocene palaeoshorelines and Late Pleistocene submerged landscapes and mapping submerged archaeological remains. The IO has been a key-partner in the Black Sea Maritime Archaeology Project, which provided a vast amount of new information on the evolution of the palaeo-shoreline and led to the discovery and documentation of dozens of ancient shipwrecks on the Black Sea’s seafloor. Many publications are co-authored by IO’s geoscientists and Greek and European archaeologists, showing the high level of interdisciplinarity accomplished and the fostering of collaboration with archaeological institutions.

Marine optics

Remote sensing products such as the ocean colour are used to assess the health and productivity of marine ecosystems, and the role of the oceans in the global carbon cycle. To date, it is known that in certain cases existing algorithms may considerably overestimate chlorophyll-a concentration by several times, particularly in ultra-oligotrophic ecosystems such as the E. Mediterranean. The IO formed a multidisciplinary group of scientists focused on the study of ocean colour and its remote sensing applications, and aiming to work towards a more accurate determination of chlorophyll-α, particulate organic carbon, and particulate matter concentrations from space (Perseus, Thales projects,). Such an achievement support the national monitoring projects of Greece by improving the spatiotemporal resolution and quality of ocean data products. The bio-optics group capitalized on previous research on particle dynamics studies by optical methods and, after acquiring new state-of-the-art equipment, progressed towards hyperspectral observations of inherent and apparent properties of seawater (IOPs and AOPs).

• 

• 

• 

In parallel, substantial effort was placed on technological developments, by designing and constructing a unique custom underwater platform that combines standard CTD measurements and hyperspectral optical measurements. The platform has been successfully deployed in cruises in the E. Mediterranean (Perseus, AegeanMarTech, Region Creta, Aegean Winter, LEVECO projects), and the Black Sea (cruise BIO-OPT).

Marine Radioactivity applications

A new GeoMAREA detection system for marine radioactivity applications has been developed, in the frame of RADIOSCOPIO project, for measuring in situ the activity concentration of gamma-ray emitters in the marine environment using medium resolution crystal and digital electronic units. The system separates different sources of artificial radioactivity due to nuclear reactors operation or accidents.

• 

• 

• 

Additionally, the existing subsea detection system KATERINA II is capable to provide real time water quality in coastal areas with enhanced non-nuclear industrial activity (bauxite, fertilizer, oil, cement and mining). The KATERINA II system has been designed for aquatic applications and has been tested and deployed in Mediterranean, Black, and Caspian Seas. Inter-calibration and inter-laboratory exercises have been performed in collaboration with international and national laboratories and networks (e.g. ALMERA, XENOKRATIS). Another version of the system was made possible for application in the Deep Ocean, the KATERINA –D system designed to offer continuous operation up to 4500m water depth. The system was used for the first time during the LEVECO project, measuring the radon progeny profiles in selected areas south of Crete Island upon mud volcanoes areas. The systems have been used in several environmental applications such as tracing of submarine groundwater discharge (projects ANAVALOS, COST-FLOWS), or pollution mapping in the frame of the IAEA Collaboration Research Projects (BEACH). All subsea radioactivity detection systems developed at the IO are capable to be integrated on floating measuring systems for real-time applications.